*Sulfer Dioxide (SO²) reacts with water to form one of the acids in acid rain. Most Sulfur dioxide (SO²) is used to make sulfuric acid (H²SO⁴) Normal Rain is already slightly acidic with a ph of 5.6, becuase of the weak acidic compound formed when the carbon dioxide reacts with the water to form a carbonic acid. "Acid" rain is formed when air pollutiants react Sulfer and Nitrogen dioxides forming acidic compounds, like Sulfuric and Nitric Acids. The primary cause of Acid rain forming is vehicle and factory pollution. Acid rain has became a bigger and bigger problem since the Industrial Revolution started, and people started to burn coal and other materials for heat and power. China, Eastern Europe, Russia, and places downwind from them all have problems with acid rain. The reason being that they burn sulfer containing coal for there electiricty and heat. Rain in these places has been known to have a PH as low as 2.4 which is below that of vinegar..
